Brooklyn Nets guard Ben Simmons ruled himself out on Friday of playing for Australia at the World Cup this year to instead focus on recovering from injuries.

The three-time NBA All Star was omitted from his country's squad named in May, but coach Brian Goorjian left the door open.

Simmons, the 2018 NBA rookie of the year, had signalled that he hoped to play after opting out of the Tokyo Olympics, but he has been out of action with a back injury.

"Ben needs more time to focus on his rehab and he looks forward to being part of the Boomers in the future," Basketball Australia said on Twitter. "We wish Ben all the best in his recovery."

The World Cup, co-hosted by Japan, Indonesia and the Philippines, runs from August 25 to September 10.

Australia, who finished fourth at the 2019 World Cup in China and third at the Tokyo Olympics, are drawn in a group alongside Japan, Finland and Germany.